A Pooled Analysis of Trastuzumab Deruxtecan in Patients With HER2-Positive Metastatic Breast Cancer With Brain Metastases.

ABSTRACT

BACKGROUND: This exploratory pooled analysis investigated the efficacy and safety of trastuzumab deruxtecan (T-DXd) versus comparator treatment in patients with HER2-positive metastatic breast cancer (mBC) with brain metastases (BMs) at baseline, categorized according to previous local treatment. PATIENTS AND METHODS: T-DXd data were pooled from DESTINY-Breast01/-02/-03. Comparator data, from patients receiving physician's choice therapy and trastuzumab emtansine, were pooled from DESTINY-Breast02 and -03, respectively. Baseline BM status was assessed according to US Food and Drug Administration criteria. Endpoints included intracranial objective response rate (ORR; complete or partial response in brain) per blinded independent central review (BICR) by RECIST v1.1, time to intracranial response, intracranial duration of response (DoR), central nervous system progression-free survival (CNS-PFS) by BICR, overall survival (OS), and safety. RESULTS: 148 patients who received T-DXd and 83 patients who received comparator treatment had BMs at baseline. In those who were treated with T-DXd, the intracranial ORR of patients with treated/stable and untreated/active BMs was 45.2% and 45.5%, respectively. The median (range) time to intracranial response was 2.8 months (1.1-13.9 months) and 1.5 months (1.2-13.7 months) in patients with treated/stable and untreated/active BMs, respectively. For those with treated/stable BMs, the median (95% CI) intracranial DoR was 12.3 months (9.1-17.9 months), and for those with untreated/active BMs it was 17.5 months (13.6-31.6 months). The median (95% CI) CNS-PFS and OS was 12.3 months (11.1-13.8 months) and not reached (22.1 months-not estimable [NE]) in those with treated/stable BMs, and 18.5 months (13.6-23.3 months) and 30.2 months (21.3 months-NE) in those with untreated/active BMs, respectively. Drug-related TEAEs grade ≥3 were experienced by 43.2% of patients with BMs and 46.4% without BMs with T-DXd. CONCLUSIONS: T-DXd demonstrated meaningful intracranial efficacy and clinical benefit in OS, with an acceptable and manageable safety profile in patients with HER2-positive mBC with treated/stable and untreated/active BMs.